Code signaling



Patented Feb. 16, 1937 UNITED STATES PATENT OFFICE CODE SIGNALING of Delaware Application July 27, 1935, Serial No. 33,509 I 6 Claims.

This invention relates to telegraph signaling apparatus, and particularly to telegraph systems for signaling by means of a special code in which the signals consist of electrical conditions which are made to persist for various time intervals and which have been termed double current cable code signals. Examples of such signaling are set forth in the specifications of British Patents Nos. 294,715 and 267,180, granted to H. V. Higgett, August 2, 1928 and March 14, 1927, respectively. The usual method of these systems consists in representing a dot by a marking current having a duration of per cent of a signaling interval, while a dash is represented by a spacing current having the same duration and a space by a marking current lasting for 50 per cent of a signaling interval followed by a second 50 per cent of spacing current. At the telegraph receiver of these systems, the signals are changed to a three element cable code by means of a differential relay having two windings one of which is responsive to a dash to move the stylus in one direction and the other of which is responsive to a dot to move the stylus in an opposite direction with respect to a central position, neither winding being responsive to a space signal which is represented by the central position.

Cable code transmitting apparatus when it is synchronously operated may be of either of two types depending upon the arrangement of contacting and insulating segments of the transmitting commutator which is adopted. In one of these types the segments are arranged to transmit positive and negative impulses with practically no appreciable intervening time intervals. In the second type, the insulating segments are more extended thus permitting short no-current time intervals to intervene between any two signalling impulses, whether successively positive, negative, or positive-negative. My invention will hereinafter be illustrated in its application to cable code transmitting systems of the second type just described.

The present invention has for its object to provide in the foregoing type of telegraph receiver an arrangement for converting the three element cable code signals into standard two element Continental code signals whereby there is obtained a two element record which may easily be read by operators skilled in Continental code operation.

Advantages of the present invention are that it affords easier monitoring of the telegraph receiving equipment of the foregoing double current cable code type, and enables the immediate reading of rush messages or breaks, consequently overcoming the delay incidental to the passage of the signals through the printer and the subsequent pasting up of the recorded signals on blanks as with normal trafiic.

In general, the present invention provides at the receiver a doublev commutator arrangement which replaces the differential recording relay of the prior art systems. A phonic motor controlled by the telegraph receiving equipment as to speed and phase is employed to drive the commutators. One of these commutators is used for the dot signal and the other for the dash, and the lengths of the commutator segments are so designed that there is obtained from the commutator signal energy of'duration which approximates the normal records of Continental code received over standard radio circuits.

In the drawing, Fig. 1 shows the form of the current waves of the letters A, B and J recorded in the three-element code;

Fig. 2 shows the same letters recorded in the two element code, in accordance with the invention; and

Fig. 3 shows a receiving arrangement, in ac- M cordance with the invention, in circuit with the contacts of the signal output relay of a telegraph receiver of the Higgett type. 7

As is well known, the signal output relay of the telegraph receiver is provided with two contactors, herein shown designated in Fig. 3 as the dot and dash contactors. The common armature of this relay 3 is provided with a source of potential 4 whose positive terminal is connected to the armature and whose negative terminal is grounded. For obtaining the two element code, there are provided commutators I and 2 driven by a phonic driving motor M which is synchronously controlled as to speed and phase in well known manner from the telegraph receiving equipment, the details of which are not shown. Connected to each commutator is a brush which connects with one of the dot and dash contactors of relay 3 and another brush which is connected to a signal recorder 6 in common with both commutators through a limiting resistor R. Recorder 6 is here shown as an ink recorder although it will be appreciated that any recorder such as a reperforator can be used.

Commutator I, which has one of its brushes connected to the dash commutator, is provided with longer conducting segments 5 than those of commutator 2 whose brush is connected with the dot contactor, in order to approximate in the recorder 6 dot and dash signals of lengths whose ratio is similar to the ratio of the lengths of the well known elements of the Continental code.

There is thus obtained by such an arrangement a record which approximates the normal records of the Continental code received over standard radio circuits, at least sufficiently so as to be readily readable by the normal skilled operator.

It will be understood, of course, that the invention is not limited to the precise details shown since variousmodifications may be made without departing from the spirit and scope of the invention. As an example, the commutator associated with the dash contactor may be completely omitted, if the input signal has a short zero time between successive units of the signal characters.

What is claimed is:

1. In a telegraph receiving system, a relay having a dot contact, a dash contact, and armature means selectively connectable with the two said contacts, said relay being responsive to current of one polarity to move said armature means in a direction for engagement with one of said contacts and responsive to current of another polarity to move said armature means in a direction for engagement with the other contact, a commutator provided with conducting segments and having a brush connected to the clot contact, a second commutator also provided with conducting segments and having a brush connected to the dash contact, a recorder, and a connection from said recorder to the segments of both of said commutators, synchronized driving means for both said commutators, the segments of one commutator having different lengths from those of the other commutator, whereby the engagement of said dot contact with said armature aifects said recorder for a different interval of time than the engagement of said dash contact with said armature.

2. A system in accordance with claim 1, characterized in this that all the segments on one commutator are of the same length, and said driving means is a motor synchronized by said receiving system as to phase and speed.

3. In a telegraph receiving system, a relay having a dot contact, a dash contact, and armature means selectively connectable with the two said contacts, said relay being responsive to current of one polarity to move said armature means in a direction for engagement with one of said contacts and responsive to current of another pclarity to move said armature means in a direction for engagement with the other contact, a commutator provided with conducting segments and having a brush connected to the dot contact, a recorder, a connection from said recorder to said dash contact, a connection from said recorder to the segments of said commutator, and synchronized driving means for said commutator whereby engagement of said dot contact with said armature and the rotation of said commutator afiects said recorder to produce two element code signals.

4. A receiving system for three element telegraph signals in wlL'ch dot, dash, and space units have different characteristics but equal time intervals, a relay having armature mechanism movable from a non-contacting position to a dot contacting and to a dash contacting position selectively and alternatively in response to dot and dash signals respectively, a commutator device driven synchronously with the signals, a twoelement recording device, and interconnecting circuits such that the relay cooperates with the commutating device to feed the recorder with dot and dash impulses of a single characteristic but of different time intervals, and space units of a different characteristic.

5. In a telegraph code transforming system, relay apparatus having a dot-contact and a dashcontact, a signal recording device in circuit with said contacts, a source of current connectable between said recording device and one or the other of said contacts in dependence upon the response of said relay apparatus to periodic posi-- tive and negative signaling impulses, a commutator in circuit between said dot contact and said recording device, and means for synchronizing the operation of said commutator with the periodicity of said signaling impulses, said commutator being characterized in that it curtails the moments of connection of said dot contact with said recording device in comparison with the duration of the holding period of said relay apparatus in response to a received dot impulse.

6. In a telegraph code transforming system, a tape recorder, a pair of operating circuits and a source of potential for feeding current to said recorder, a motor-operated commutator arrangement for limiting the duration of dot and dash impulses applied to said recorder, the duration of each of said dot impulses being more limited than that of said dash impulses, by virtue of the time constants inherent in the construction and operation of said commutator arrangement, means for running said motor-operated commutator arrangement synchronously with the periodic reception of signaling impulses, and relay means having a dot contact and a dash contact, the last said means being responsive to said signaling impulses for closing said contacts selectively during uniform time periods spaced apart by short no-current time intervals.

RICHARD E. MATHES. 

